scholarly journals Fermentation of Organic Residues to Beneficial Chemicals: A Review of Medium-Chain Fatty Acid Production

Processes ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 1571
Author(s):  
Panagiota Stamatopoulou ◽  
Juliet Malkowski ◽  
Leandro Conrado ◽  
Kennedy Brown ◽  
Matthew Scarborough
Keyword(s):  
Organic Waste ◽  
Chain Elongation ◽  
Organic Substrates ◽  
Industrial Chemicals ◽  
Waste Streams ◽  
Fatty Acid Production ◽  
Medium Chain ◽  
Renewable Feedstocks ◽  
History Of ◽  
Complex Organic

Medium-chain fatty acids (MCFAs) have a variety of uses in the production of industrial chemicals, food, and personal care products. These compounds are often produced through palm refining, but recent work has demonstrated that MCFAs can also be produced through the fermentation of complex organic substrates, including organic waste streams. While “chain elongation” offers a renewable platform for producing MCFAs, there are several limitations that need to be addressed before full-scale implementation becomes widespread. Here, we review the history of work on MCFA production by both pure and mixed cultures of fermenting organisms, and the unique metabolic features that lead to MCFA production. We also offer approaches to address the remaining challenges and increase MCFA production from renewable feedstocks.

scholarly journals Medium Chain Carboxylic Acids from Complex Organic Feedstocks by Mixed Culture Fermentation

Molecules ◽  
2019 ◽  
Vol 24 (3) ◽  
pp. 398 ◽  
Author(s):  
Vicky De Groof ◽  
Marta Coma ◽  
Tom Arnot ◽  
David J Leak ◽  
Ana B Lanham
Keyword(s):  
Carboxylic Acids ◽  
Organic Waste ◽  
Chain Elongation ◽  
Operational Parameters ◽  
Critical Research ◽  
Environmental Pressures ◽  
Mixed Culture Fermentation ◽  
Renewable Chemicals ◽  
Medium Chain ◽  
Complex Organic

Environmental pressures caused by population growth and consumerism require the development of resource recovery from waste, hence a circular economy approach. The production of chemicals and fuels from organic waste using mixed microbial cultures (MMC) has become promising. MMC use the synergy of bio-catalytic activities from different microorganisms to transform complex organic feedstock, such as by-products from food production and food waste. In the absence of oxygen, the feedstock can be converted into biogas through the established anaerobic digestion (AD) approach. The potential of MMC has shifted to production of intermediate AD compounds as precursors for renewable chemicals. A particular set of anaerobic pathways in MMC fermentation, known as chain elongation, can occur under specific conditions producing medium chain carboxylic acids (MCCAs) with higher value than biogas and broader applicability. This review introduces the chain elongation pathway and other bio-reactions occurring during MMC fermentation. We present an overview of the complex feedstocks used, and pinpoint the main operational parameters for MCCAs production such as temperature, pH, loading rates, inoculum, head space composition, and reactor design. The review evaluates the key findings of MCCA production using MMC, and concludes by identifying critical research targets to drive forward this promising technology as a valorisation method for complex organic waste.

scholarly journals Multi-omic analysis of medium-chain fatty acid synthesis by Candidatus Weimerbacter bifidus, gen. nov., sp. nov., and Candidatus Pseudoramibacter fermentans, sp. nov.

2019 ◽  
Author(s):  
Matthew J. Scarborough ◽  
Kevin S. Myers ◽  
Timothy J. Donohue ◽  
Daniel R. Noguera
Keyword(s):  
Fatty Acids ◽  
Acid Synthesis ◽  
Chain Elongation ◽  
Industrial Chemicals ◽  
Culture Studies ◽  
Medium Chain ◽  
Medium Chain Fatty Acids ◽  
Metabolic Functions ◽  
Energy Conserving ◽  
Chain Fatty Acids

ABSTRACTChain elongation is emerging as a bioprocess to produce valuable medium-chain fatty acids (MCFA; 6 to 8 carbons in length) from organic waste streams by harnessing the metabolism of anaerobic microbiomes. Although our understanding of chain elongation physiology is still evolving, the reverse β-oxidation pathway has been identified as a key metabolic function to elongate the intermediate products of fermentation to MCFA. Here, we describe two chain-elongating microorganisms that were enriched in an anaerobic microbiome transforming the residues from a lignocellulosic biorefining process to short- and medium-chain fatty acids. Based on a multi-omic analysis of this microbiome, we predict that Candidatus Weimerbacter bifidus, gen. nov., sp. nov. used xylose to produce MCFA, whereas Candidatus Pseudoramibacter fermentans, sp. nov., used glycerol and lactate as substrates for chain elongation. Both organisms are predicted to use an energy conserving hydrogenase to improve the overall bioenergetics of MCFA production.IMPORTANCEMicrobiomes are vital to human health, agriculture, environmental processes, and are receiving attention as biological catalysts for production of renewable industrial chemicals. Chain elongation by MCFA-producing microbiomes offer an opportunity to produce valuable chemicals from organic streams that otherwise would be considered waste. However, the physiology and energetics of chain elongation is only beginning to be studied, and we are analyzing MCFA production by self-assembled communities to complement the knowledge that has been acquired from pure culture studies. Through a multi-omic analysis of an MCFA-producing microbiome, we characterized metabolic functions of two chain elongating bacteria and predict previously unreported features of this process.

scholarly journals Fate of influent microbial populations during medium chain carboxylic acid recovery from brewery and pre-fermented food waste streams

2022 ◽  
Author(s):  
Shilva Shrestha ◽  
Brittany Colcord ◽  
Xavier Fonoll ◽  
Lutgarde Raskin
Keyword(s):  
Carboxylic Acid ◽  
Microbial Communities ◽  
Food Waste ◽  
Fermented Food ◽  
Chain Elongation ◽  
Microbial Populations ◽  
Waste Streams ◽  
Medium Chain ◽  
Acid Recovery

Waste streams continuously introduce active and inactive microbial populations that can influence assembly of microbial communities in chain elongation systems.

scholarly journals Microbial ecological mechanism for long-term production of high concentrations of n-caproate via lactate-driven chain elongation

2021 ◽  
Author(s):  
Xiaoyu Zhu ◽  
Xin Feng ◽  
Cheng Liang ◽  
Jiabao Li ◽  
Jia Jia ◽  
...  
Keyword(s):  
Organic Waste ◽  
Metagenomic Data ◽  
Chain Elongation ◽  
Human Society ◽  
Waste Streams ◽  
Term Operation ◽  
The Core ◽  
Microbial Network ◽  
High Concentrations

Lactate-driven chain elongation (LCE) has emerged as a new biotechnology to upgrade organic waste streams into valuable biochemical and fuel precursor, medium chain carboxylate, n-caproate. Considering that a low cost of downstream extraction is critical for biorefinery technology, a high concentration of n-caproate production is very important to improve the scale-up of the LCE process. We report here that in a nonsterile open environment, the n-caproate concentration was increased from the previous record of 25.7 g·L−1 to a new high level of 33.7 g·L−1 (76.8 g COD·L−1), with the highest production rate of 11.5 g·L−1·d−1 (26.2 g COD·L−1·d−1). In addition, the LCE process remained stable with an average concentration of n-caproate production of 20.2 ± 5.62 g·L−1 (46.1 ± 12.8 g COD·L−1) for 780 days. Dynamic changes in taxonomic composition integrated with metagenomic data reveal the microbial ecology for long-term production of high concentrations of n-caproate: 1) the core microbiome is related to efficient functional groups, such as Ruminococcaceae (with functional strain CPB6); 2) the core bacteria can maintain stability for long-term operation; 3) the microbial network has relatively low microbe-microbe interaction strength; and 4) low relative abundance and variety of competitors. The network structure could be shaped by hydraulic retention time (HRT) over time, and long-term operation at an HRT of 8 days displayed higher efficacy. IMPORTANCE Our research revealed the microbial network of LCE reactor microbiome for n-caproate production at high concentrations, which will provide a foundation for designing or engineering the LCE reactor microbiome to recover n-caproate from organic waste streams in the future. In addition, the hypothetical model of the reactor microbiome that we proposed may offer guidance for researchers to find the underlying microbial mechanism when they encounter low-efficiency n-caproate production from the LCE process. We anticipate that our research will rapidly advance LCE biotechnology with the goal of promoting the sustainable development of human society.

A comprehensive overview and recent advances on polyhydroxyalkanoates (PHA) production using various organic waste streams

2021 ◽  
Vol 325 ◽  
pp. 124685
Author(s):  
Rijuta Ganesh Saratale ◽  
Si-Kyung Cho ◽  
Ganesh Dattatraya Saratale ◽  
Avinash A. Kadam ◽  
Gajanan S. Ghodake ◽  
...  
Keyword(s):  
Organic Waste ◽  
Waste Streams ◽  
Comprehensive Overview ◽  
Recent Advances ◽  
Pha Production
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